204 N. Annandalr : The Fauna of Brackish Ponds. [VOL. I, 



two species frequently occurring together on the same stem or 

 root and their zoaria being very closely interlocked. B. caudata is, 

 however, generally more restricted as to the area it covers than 

 V . pavida, which as a rule surrounds it when the two are found in 

 close contact. In such circumstances it is by no means easy, 

 distinct as the species really are, to distinguish one from the other. 

 The bases of the zoaria are almost invariably concealed by a dense 

 growth of minute algae and other organisms, and, except when 

 buds are being produced on the zooecia by Victorella, the distal 

 ends of the zooecia are extraordinarily alike. The basal portion of 

 these structures, when it is visible or if it can be freed from ex- 

 ternal matter, affords the best means of diagnosis. The nature of 

 this part of the organism has already been fully dealt with in the 

 case of one species ; in the other, B. caudata, the zocecia adhere to 

 the sides of the stolon and end in each case in a free conical " tail," 

 which as a rule hangs down beneath the level of the stolon. This 

 character is often to some extent obscured in old individuals, 

 although very clear in some zooecia of every zoarium. 



If the polypides are alive and can be induced to expand their 

 lophophpres while under observation, the readiest way to distin- 

 guish Victorella from Bowerbankia is to note that whereas the gizzard 

 is highly muscular in the latter, its walls are thin in the former. 

 In living examples of the two forms this character is conspicuous 

 when the tentacles are extruded, and can be detected with a little 

 care even when they are retracted ; but in preserved material it is 

 often difficult to be sure as regards the nature of the gizzard, which 

 is clearly present (as Bousfield noticed) even in Victorella. 



My specimens of B. caudata agree fairl^^ well with Hincks's 

 figures, but the " tail " of the zooecia is sometimes longer and occa- 

 sionally forks at its free extremity, the alternate arrangement of the 

 zooecia is not quite constant, and the stolon is divided by partitions 

 placed at irregular intervals. When the zoarium becomes much 

 matted together, the "tails " appear to grow longer than is the case 

 when the colony has plenty of room for expansion, and sometimes 

 secondary adhesions are formed both between the " tail " and 

 another loop of the stolon and between different parts of the 

 stolon. When the tails adhere to the stolon in this way they do so 

 either by their sides or by their tips. 



The tentacles, which always number eight, bear at their base. a 

 long sensory bristle (which slopes backwards and downwards when 

 the lophophore is expanded) and a series of three or four approxim- 

 ately horizontal, finer hairs on their external surface, as well as a 

 bunch of still finer hairs at their tip. 



Specimens taken during winter were sexually mature, the gonads 

 closely resembling those of Victorella. In most cases, however, the 

 testes became mature before the ovaries. Colonies kept through 

 the hot weather in an aquarium in which the salinity of the water 

 was maintained at an even level, continued to produce spermatozoa 

 until the end of June and did not form brown bodies. I failed 

 to observe the formation of ovaries in these circumstances. It is 



